Bitplane area correlator

Claim 1

A semiconductor chip for comparing an image formed by a plurality of pixels to a mask formed by a plurality of pixels, comprising: a first memory for storing a plurality of bits representing a contiguous plurality of said mask pixels; a second memory for storing a plurality of bits representing a contiguous plurality of said image pixels larger in number than said plurality of mask pixels; a plurality of input lines coupled to data inputs of said second memory; a plurality of means for comparing said mask pixel bits to a combination of said image pixel bits; first bus means for coupling said first memory to all of said means for comparing; second bus means for coupling each output of said second memory to a plurality of said means for comparing such that each portion of said image pixel bits representing a single pixel is coupled to a different position in each of a plurality of said means for comparing, whereby a different combination of said image pixel bits is provided to each of said means for comparing, such that simultaneous comparisons, without requiring additional inputs, are provided for different offsets of groups of pixels in said image; means for counting the number of digital ones or zeroes in a result of said comparison and producing a digital tally of said number for each said combination; means for accumulating said tallies separately for each said combination; means for algebraically combining a tally of a second mask comparison with said accumulated tally for said combination; and means for selecting from among said accumulated tallies for said combinations a best match of said image to said masks and providing said best match to an output line.